<?php

// +----------------------------------------------------------------------

// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]

// +----------------------------------------------------------------------

// | Copyright (c) 2006-2013 http://thinkphp.cn All rights reserved.

// +----------------------------------------------------------------------

// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )

// +----------------------------------------------------------------------

// | Author: liu21st <liu21st@gmail.com>

// +----------------------------------------------------------------------

namespace Think;

/**

 * ThinkPHP 数据库中间层实现类

 */

class Db {

    // 数据库类型

    protected $dbType     = null;

    // 是否自动释放查询结果

    protected $autoFree   = false;

    // 当前操作所属的模型名

    protected $model      = '_think_';

    // 是否使用永久连接

    protected $pconnect   = false;

    // 当前SQL指令

    protected $queryStr   = '';

    protected $modelSql   = array();

    // 最后插入ID

    protected $lastInsID  = null;

    // 返回或者影响记录数

    protected $numRows    = 0;

    // 返回字段数

    protected $numCols    = 0;

    // 事务指令数

    protected $transTimes = 0;

    // 错误信息

    protected $error      = '';

    // 数据库连接ID 支持多个连接

    protected $linkID     = array();

    // 当前连接ID

    protected $_linkID    = null;

    // 当前查询ID

    protected $queryID    = null;

    // 是否已经连接数据库

    protected $connected  = false;

    // 数据库连接参数配置

    protected $config     = '';

    // 数据库表达式

    protected $comparison = array('eq'=>'=','neq'=>'<>','gt'=>'>','egt'=>'>=','lt'=>'<','elt'=>'<=','notlike'=>'NOT LIKE','like'=>'LIKE','in'=>'IN','notin'=>'NOT IN');

    // 查询表达式

    protected $selectSql  = 'SELECT%DISTINCT% %FIELD% FROM %TABLE%%JOIN%%WHERE%%GROUP%%HAVING%%ORDER%%LIMIT% %UNION%%COMMENT%';

    // 参数绑定

    protected $bind       = array();



    /**

     * 取得数据库类实例

     * @static

     * @access public

     * @return mixed 返回数据库驱动类

     */

    public static function getInstance($db_config='') {

		static $_instance	=	array();

		$guid	=	to_guid_string($db_config);

		if(!isset($_instance[$guid])){

			$obj	=	new Db();

			$_instance[$guid]	=	$obj->factory($db_config);

		}

		return $_instance[$guid];

    }



    /**

     * 加载数据库 支持配置文件或者 DSN

     * @access public

     * @param mixed $db_config 数据库配置信息

     * @return string

     */

    public function factory($db_config='') {

        // 读取数据库配置

        $db_config = $this->parseConfig($db_config);

        if(empty($db_config['dbms']))

            E(L('_NO_DB_CONFIG_'));

        // 数据库类型

        if(strpos($db_config['dbms'],'\\')){

            $class  =   $db_config['dbms'];

        }else{

            $dbType =   ucwords(strtolower($db_config['dbms']));

            $class  =   'Think\\Db\\Driver\\'. $dbType;            

        }

        // 检查驱动类

        if(class_exists($class)) {

            $db = new $class($db_config);

        }else {

            // 类没有定义

            E(L('_NO_DB_DRIVER_').': ' . $class);

        }

        return $db;

    }



    /**

     * 根据DSN获取数据库类型 返回大写

     * @access protected

     * @param string $dsn  dsn字符串

     * @return string

     */

    protected function _getDsnType($dsn) {

        $match  =  explode(':',$dsn);

        $dbType = strtoupper(trim($match[0]));

        return $dbType;

    }



    /**

     * 分析数据库配置信息，支持数组和DSN

     * @access private

     * @param mixed $db_config 数据库配置信息

     * @return string

     */

    private function parseConfig($db_config='') {

        if ( !empty($db_config) && is_string($db_config)) {

            // 如果DSN字符串则进行解析

            $db_config = $this->parseDSN($db_config);

        }elseif(is_array($db_config)) { // 数组配置

             $db_config =   array_change_key_case($db_config);

             $db_config = array(

                  'dbms'      =>  $db_config['db_type'],

                  'username'  =>  $db_config['db_user'],

                  'password'  =>  $db_config['db_pwd'],

                  'hostname'  =>  $db_config['db_host'],

                  'hostport'  =>  $db_config['db_port'],

                  'database'  =>  $db_config['db_name'],

                  'dsn'       =>  $db_config['db_dsn'],

                  'params'    =>  $db_config['db_params'],

             );

        }elseif(empty($db_config)) {

            // 如果配置为空，读取配置文件设置

            if( C('DB_DSN') && 'pdo' != strtolower(C('DB_TYPE')) ) { // 如果设置了DB_DSN 则优先

                $db_config =  $this->parseDSN(C('DB_DSN'));

            }else{

                $db_config = array (

                    'dbms'      =>  C('DB_TYPE'),

                    'username'  =>  C('DB_USER'),

                    'password'  =>  C('DB_PWD'),

                    'hostname'  =>  C('DB_HOST'),

                    'hostport'  =>  C('DB_PORT'),

                    'database'  =>  C('DB_NAME'),

                    'dsn'       =>  C('DB_DSN'),

                    'params'    =>  C('DB_PARAMS'),

                );

            }

        }

        return $db_config;

    }



    /**

     * 初始化数据库连接

     * @access protected

     * @param boolean $master 主服务器

     * @return void

     */

    protected function initConnect($master=true) {

        if(1 == C('DB_DEPLOY_TYPE'))

            // 采用分布式数据库

            $this->_linkID = $this->multiConnect($master);

        else

            // 默认单数据库

            if ( !$this->connected ) $this->_linkID = $this->connect();

    }



    /**

     * 连接分布式服务器

     * @access protected

     * @param boolean $master 主服务器

     * @return void

     */

    protected function multiConnect($master=false) {

        static $_config = array();

        if(empty($_config)) {

            // 缓存分布式数据库配置解析

            foreach ($this->config as $key=>$val){

                $_config[$key]      =   explode(',',$val);

            }

        }

        // 数据库读写是否分离

        if(C('DB_RW_SEPARATE')){

            // 主从式采用读写分离

            if($master)

                // 主服务器写入

                $r  =   floor(mt_rand(0,C('DB_MASTER_NUM')-1));

            else{

                if(is_numeric(C('DB_SLAVE_NO'))) {// 指定服务器读

                    $r = C('DB_SLAVE_NO');

                }else{

                    // 读操作连接从服务器

                    $r = floor(mt_rand(C('DB_MASTER_NUM'),count($_config['hostname'])-1));   // 每次随机连接的数据库

                }

            }

        }else{

            // 读写操作不区分服务器

            $r = floor(mt_rand(0,count($_config['hostname'])-1));   // 每次随机连接的数据库

        }

        $db_config = array(

            'username'  =>  isset($_config['username'][$r])?$_config['username'][$r]:$_config['username'][0],

            'password'  =>  isset($_config['password'][$r])?$_config['password'][$r]:$_config['password'][0],

            'hostname'  =>  isset($_config['hostname'][$r])?$_config['hostname'][$r]:$_config['hostname'][0],

            'hostport'  =>  isset($_config['hostport'][$r])?$_config['hostport'][$r]:$_config['hostport'][0],

            'database'  =>  isset($_config['database'][$r])?$_config['database'][$r]:$_config['database'][0],

            'dsn'       =>  isset($_config['dsn'][$r])?$_config['dsn'][$r]:$_config['dsn'][0],

            'params'    =>  isset($_config['params'][$r])?$_config['params'][$r]:$_config['params'][0],

        );

        return $this->connect($db_config,$r);

    }



    /**

     * DSN解析

     * 格式： mysql://username:passwd@localhost:3306/DbName

     * @static

     * @access public

     * @param string $dsnStr

     * @return array

     */

    public function parseDSN($dsnStr) {

        if( empty($dsnStr) ){return false;}

        $info = parse_url($dsnStr);

        if($info['scheme']){

            $dsn = array(

            'dbms'      =>  $info['scheme'],

            'username'  =>  isset($info['user']) ? $info['user'] : '',

            'password'  =>  isset($info['pass']) ? $info['pass'] : '',

            'hostname'  =>  isset($info['host']) ? $info['host'] : '',

            'hostport'  =>  isset($info['port']) ? $info['port'] : '',

            'database'  =>  isset($info['path']) ? substr($info['path'],1) : ''

            );

        }else {

            preg_match('/^(.*?)\:\/\/(.*?)\:(.*?)\@(.*?)\:([0-9]{1, 6})\/(.*?)$/',trim($dsnStr),$matches);

            $dsn = array (

            'dbms'      =>  $matches[1],

            'username'  =>  $matches[2],

            'password'  =>  $matches[3],

            'hostname'  =>  $matches[4],

            'hostport'  =>  $matches[5],

            'database'  =>  $matches[6]

            );

        }

        $dsn['dsn'] =  ''; // 兼容配置信息数组

        return $dsn;

     }



    /**

     * 数据库调试 记录当前SQL

     * @access protected

     */

    protected function debug() {

        $this->modelSql[$this->model]   =  $this->queryStr;

        $this->model  =   '_think_';

        // 记录操作结束时间

        if (C('DB_SQL_LOG')) {

            G('queryEndTime');

            trace($this->queryStr.' [ RunTime:'.G('queryStartTime','queryEndTime',6).'s ]','','SQL');

        }

    }



    /**

     * 设置锁机制

     * @access protected

     * @return string

     */

    protected function parseLock($lock=false) {

        if(!$lock) return '';

        if('ORACLE' == $this->dbType) {

            return ' FOR UPDATE NOWAIT ';

        }

        return ' FOR UPDATE ';

    }



    /**

     * set分析

     * @access protected

     * @param array $data

     * @return string

     */

    protected function parseSet($data) {

        foreach ($data as $key=>$val){

            if(is_array($val) && 'exp' == $val[0]){

                $set[]  =   $this->parseKey($key).'='.$val[1];

            }elseif(is_scalar($val) || is_null($val)) { // 过滤非标量数据

              if(C('DB_BIND_PARAM') && 0 !== strpos($val,':')){

                $name   =   md5($key);

                $set[]  =   $this->parseKey($key).'=:'.$name;

                $this->bindParam($name,$val);

              }else{

                $set[]  =   $this->parseKey($key).'='.$this->parseValue($val);

              }

            }

        }

        return ' SET '.implode(',',$set);

    }



     /**

     * 参数绑定

     * @access protected

     * @param string $name 绑定参数名

     * @param mixed $value 绑定值

     * @return void

     */

    protected function bindParam($name,$value){

        $this->bind[':'.$name]  =   $value;

    }



     /**

     * 参数绑定分析

     * @access protected

     * @param array $bind

     * @return array

     */

    protected function parseBind($bind){

        $bind           =   array_merge($this->bind,$bind);

        $this->bind     =   array();

        return $bind;

    }



    /**

     * 字段名分析

     * @access protected

     * @param string $key

     * @return string

     */

    protected function parseKey(&$key) {

        return $key;

    }

    

    /**

     * value分析

     * @access protected

     * @param mixed $value

     * @return string

     */

    protected function parseValue($value) {

        if(is_string($value)) {

            $value =  '\''.$this->escapeString($value).'\'';

        }elseif(isset($value[0]) && is_string($value[0]) && strtolower($value[0]) == 'exp'){

            $value =  $this->escapeString($value[1]);

        }elseif(is_array($value)) {

            $value =  array_map(array($this, 'parseValue'),$value);

        }elseif(is_bool($value)){

            $value =  $value ? '1' : '0';

        }elseif(is_null($value)){

            $value =  'null';

        }

        return $value;

    }



    /**

     * field分析

     * @access protected

     * @param mixed $fields

     * @return string

     */

    protected function parseField($fields) {

        if(is_string($fields) && strpos($fields,',')) {

            $fields    = explode(',',$fields);

        }

        if(is_array($fields)) {

            // 完善数组方式传字段名的支持

            // 支持 'field1'=>'field2' 这样的字段别名定义

            $array   =  array();

            foreach ($fields as $key=>$field){

                if(!is_numeric($key))

                    $array[] =  $this->parseKey($key).' AS '.$this->parseKey($field);

                else

                    $array[] =  $this->parseKey($field);

            }

            $fieldsStr = implode(',', $array);

        }elseif(is_string($fields) && !empty($fields)) {

            $fieldsStr = $this->parseKey($fields);

        }else{

            $fieldsStr = '*';

        }

        //TODO 如果是查询全部字段，并且是join的方式，那么就把要查的表加个别名，以免字段被覆盖

        return $fieldsStr;

    }



    /**

     * table分析

     * @access protected

     * @param mixed $table

     * @return string

     */

    protected function parseTable($tables) {

        if(is_array($tables)) {// 支持别名定义

            $array   =  array();

            foreach ($tables as $table=>$alias){

                if(!is_numeric($table))

                    $array[] =  $this->parseKey($table).' '.$this->parseKey($alias);

                else

                    $array[] =  $this->parseKey($table);

            }

            $tables  =  $array;

        }elseif(is_string($tables)){

            $tables  =  explode(',',$tables);

            array_walk($tables, array(&$this, 'parseKey'));

        }

        $tables = implode(',',$tables);

        return $tables;

    }



    /**

     * where分析

     * @access protected

     * @param mixed $where

     * @return string

     */

    protected function parseWhere($where) {

        $whereStr = '';

        if(is_string($where)) {

            // 直接使用字符串条件

            $whereStr = $where;

        }else{ // 使用数组表达式

            $operate  = isset($where['_logic'])?strtoupper($where['_logic']):'';

            if(in_array($operate,array('AND','OR','XOR'))){

                // 定义逻辑运算规则 例如 OR XOR AND NOT

                $operate    =   ' '.$operate.' ';

                unset($where['_logic']);

            }else{

                // 默认进行 AND 运算

                $operate    =   ' AND ';

            }

            foreach ($where as $key=>$val){

                $whereStr .= '( ';

                if(is_numeric($key)){

                    $key  = '_complex';

                }                    

                if(0===strpos($key,'_')) {

                    // 解析特殊条件表达式

                    $whereStr   .= $this->parseThinkWhere($key,$val);

                }else{

                    // 查询字段的安全过滤

                    if(!preg_match('/^[A-Z_\|\&\-.a-z0-9\(\)\,]+$/',trim($key))){

                        E(L('_EXPRESS_ERROR_').':'.$key);

                    }

                    // 多条件支持

                    $multi  = is_array($val) &&  isset($val['_multi']);

                    $key    = trim($key);

                    if(strpos($key,'|')) { // 支持 name|title|nickname 方式定义查询字段

                        $array =  explode('|',$key);

                        $str   =  array();

                        foreach ($array as $m=>$k){

                            $v =  $multi?$val[$m]:$val;

                            $str[]   = '('.$this->parseWhereItem($this->parseKey($k),$v).')';

                        }

                        $whereStr .= implode(' OR ',$str);

                    }elseif(strpos($key,'&')){

                        $array =  explode('&',$key);

                        $str   =  array();

                        foreach ($array as $m=>$k){

                            $v =  $multi?$val[$m]:$val;

                            $str[]   = '('.$this->parseWhereItem($this->parseKey($k),$v).')';

                        }

                        $whereStr .= implode(' AND ',$str);

                    }else{

                        $whereStr .= $this->parseWhereItem($this->parseKey($key),$val);

                    }

                }

                $whereStr .= ' )'.$operate;

            }

            $whereStr = substr($whereStr,0,-strlen($operate));

        }

        return empty($whereStr)?'':' WHERE '.$whereStr;

    }



    // where子单元分析

    protected function parseWhereItem($key,$val) {

        $whereStr = '';

        if(is_array($val)) {

            if(is_string($val[0])) {

                if(preg_match('/^(EQ|NEQ|GT|EGT|LT|ELT)$/i',$val[0])) { // 比较运算

                    $whereStr .= $key.' '.$this->comparison[strtolower($val[0])].' '.$this->parseValue($val[1]);

                }elseif(preg_match('/^(NOTLIKE|LIKE)$/i',$val[0])){// 模糊查找

                    if(is_array($val[1])) {

                        $likeLogic  =   isset($val[2])?strtoupper($val[2]):'OR';

                        if(in_array($likeLogic,array('AND','OR','XOR'))){

                            $likeStr    =   $this->comparison[strtolower($val[0])];

                            $like       =   array();

                            foreach ($val[1] as $item){

                                $like[] = $key.' '.$likeStr.' '.$this->parseValue($item);

                            }

                            $whereStr .= '('.implode(' '.$likeLogic.' ',$like).')';                          

                        }

                    }else{

                        $whereStr .= $key.' '.$this->comparison[strtolower($val[0])].' '.$this->parseValue($val[1]);

                    }

                }elseif('exp'==strtolower($val[0])){ // 使用表达式

                    $whereStr .= ' ('.$key.' '.$val[1].') ';

                }elseif(preg_match('/IN/i',$val[0])){ // IN 运算

                    if(isset($val[2]) && 'exp'==$val[2]) {

                        $whereStr .= $key.' '.strtoupper($val[0]).' '.$val[1];

                    }else{

                        if(is_string($val[1])) {

                             $val[1] =  explode(',',$val[1]);

                        }

                        $zone      =   implode(',',$this->parseValue($val[1]));

                        $whereStr .= $key.' '.strtoupper($val[0]).' ('.$zone.')';

                    }

                }elseif(preg_match('/BETWEEN/i',$val[0])){ // BETWEEN运算

                    $data = is_string($val[1])? explode(',',$val[1]):$val[1];

                    $whereStr .=  ' ('.$key.' '.strtoupper($val[0]).' '.$this->parseValue($data[0]).' AND '.$this->parseValue($data[1]).' )';

                }else{

                    E(L('_EXPRESS_ERROR_').':'.$val[0]);

                }

            }else {

                $count = count($val);

                $rule  = isset($val[$count-1]) ? (is_array($val[$count-1]) ? strtoupper($val[$count-1][0]) : strtoupper($val[$count-1]) ) : '' ; 

                if(in_array($rule,array('AND','OR','XOR'))) {

                    $count  = $count -1;

                }else{

                    $rule   = 'AND';

                }

                for($i=0;$i<$count;$i++) {

                    $data = is_array($val[$i])?$val[$i][1]:$val[$i];

                    if('exp'==strtolower($val[$i][0])) {

                        $whereStr .= '('.$key.' '.$data.') '.$rule.' ';

                    }else{

                        $whereStr .= '('.$this->parseWhereItem($key,$val[$i]).') '.$rule.' ';

                    }

                }

                $whereStr = substr($whereStr,0,-4);

            }

        }else {

            //对字符串类型字段采用模糊匹配

            if(C('DB_LIKE_FIELDS') && preg_match('/('.C('DB_LIKE_FIELDS').')/i',$key)) {

                $val  =  '%'.$val.'%';

                $whereStr .= $key.' LIKE '.$this->parseValue($val);

            }else {

                $whereStr .= $key.' = '.$this->parseValue($val);

            }

        }

        return $whereStr;

    }



    /**

     * 特殊条件分析

     * @access protected

     * @param string $key

     * @param mixed $val

     * @return string

     */

    protected function parseThinkWhere($key,$val) {

        $whereStr   = '';

        switch($key) {

            case '_string':

                // 字符串模式查询条件

                $whereStr = $val;

                break;

            case '_complex':

                // 复合查询条件

                $whereStr   =   is_string($val)? $val : substr($this->parseWhere($val),6);

                break;

            case '_query':

                // 字符串模式查询条件

                parse_str($val,$where);

                if(isset($where['_logic'])) {

                    $op   =  ' '.strtoupper($where['_logic']).' ';

                    unset($where['_logic']);

                }else{

                    $op   =  ' AND ';

                }

                $array   =  array();

                foreach ($where as $field=>$data)

                    $array[] = $this->parseKey($field).' = '.$this->parseValue($data);

                $whereStr   = implode($op,$array);

                break;

        }

        return $whereStr;

    }



    /**

     * limit分析

     * @access protected

     * @param mixed $lmit

     * @return string

     */

    protected function parseLimit($limit) {

        return !empty($limit)?   ' LIMIT '.$limit.' ':'';

    }



    /**

     * join分析

     * @access protected

     * @param array $join

     * @return string

     */

    protected function parseJoin($join) {

        $joinStr = '';

        if(!empty($join)) {

            $joinStr    =   ' '.implode(' ',$join).' ';

        }

        return $joinStr;

    }



    /**

     * order分析

     * @access protected

     * @param mixed $order

     * @return string

     */

    protected function parseOrder($order) {

        if(is_array($order)) {

            $array   =  array();

            foreach ($order as $key=>$val){

                if(is_numeric($key)) {

                    $array[] =  $this->parseKey($val);

                }else{

                    $array[] =  $this->parseKey($key).' '.$val;

                }

            }

            $order   =  implode(',',$array);

        }

        return !empty($order)?  ' ORDER BY '.$order:'';

    }



    /**

     * group分析

     * @access protected

     * @param mixed $group

     * @return string

     */

    protected function parseGroup($group) {

        return !empty($group)? ' GROUP BY '.$group:'';

    }



    /**

     * having分析

     * @access protected

     * @param string $having

     * @return string

     */

    protected function parseHaving($having) {

        return  !empty($having)?   ' HAVING '.$having:'';

    }



    /**

     * comment分析

     * @access protected

     * @param string $comment

     * @return string

     */

    protected function parseComment($comment) {

        return  !empty($comment)?   ' /* '.$comment.' */':'';

    }



    /**

     * distinct分析

     * @access protected

     * @param mixed $distinct

     * @return string

     */

    protected function parseDistinct($distinct) {

        return !empty($distinct)?   ' DISTINCT ' :'';

    }



    /**

     * union分析

     * @access protected

     * @param mixed $union

     * @return string

     */

    protected function parseUnion($union) {

        if(empty($union)) return '';

        if(isset($union['_all'])) {

            $str  =   'UNION ALL ';

            unset($union['_all']);

        }else{

            $str  =   'UNION ';

        }

        foreach ($union as $u){

            $sql[] = $str.(is_array($u)?$this->buildSelectSql($u):$u);

        }

        return implode(' ',$sql);

    }



    /**

     * 插入记录

     * @access public

     * @param mixed $data 数据

     * @param array $options 参数表达式

     * @param boolean $replace 是否replace

     * @return false | integer

     */

    public function insert($data,$options=array(),$replace=false) {

        $values  =  $fields    = array();

        $this->model  =   $options['model'];

        foreach ($data as $key=>$val){

            if(is_array($val) && 'exp' == $val[0]){

                $fields[]   =  $this->parseKey($key);

                $values[]   =  $val[1];

            }elseif(is_scalar($val) || is_null($val)) { // 过滤非标量数据

              $fields[]   =  $this->parseKey($key);

              if(C('DB_BIND_PARAM') && 0 !== strpos($val,':')){

                $name       =   md5($key);

                $values[]   =   ':'.$name;

                $this->bindParam($name,$val);

              }else{

                $values[]   =  $this->parseValue($val);

              }                

            }

        }

        $sql   =  ($replace?'REPLACE':'INSERT').' INTO '.$this->parseTable($options['table']).' ('.implode(',', $fields).') VALUES ('.implode(',', $values).')';

        $sql   .= $this->parseLock(isset($options['lock'])?$options['lock']:false);

        $sql   .= $this->parseComment(!empty($options['comment'])?$options['comment']:'');

        return $this->execute($sql,$this->parseBind(!empty($options['bind'])?$options['bind']:array()));

    }



    /**

     * 通过Select方式插入记录

     * @access public

     * @param string $fields 要插入的数据表字段名

     * @param string $table 要插入的数据表名

     * @param array $option  查询数据参数

     * @return false | integer

     */

    public function selectInsert($fields,$table,$options=array()) {

        $this->model  =   $options['model'];

        if(is_string($fields))   $fields    = explode(',',$fields);

        array_walk($fields, array($this, 'parseKey'));

        $sql   =    'INSERT INTO '.$this->parseTable($table).' ('.implode(',', $fields).') ';

        $sql   .= $this->buildSelectSql($options);

        return $this->execute($sql,$this->parseBind(!empty($options['bind'])?$options['bind']:array()));

    }



    /**

     * 更新记录

     * @access public

     * @param mixed $data 数据

     * @param array $options 表达式

     * @return false | integer

     */

    public function update($data,$options) {

        $this->model  =   $options['model'];

        $sql   = 'UPDATE '

            .$this->parseTable($options['table'])

            .$this->parseSet($data)

            .$this->parseWhere(!empty($options['where'])?$options['where']:'')

            .$this->parseOrder(!empty($options['order'])?$options['order']:'')

            .$this->parseLimit(!empty($options['limit'])?$options['limit']:'')

            .$this->parseLock(isset($options['lock'])?$options['lock']:false)

            .$this->parseComment(!empty($options['comment'])?$options['comment']:'');

        return $this->execute($sql,$this->parseBind(!empty($options['bind'])?$options['bind']:array()));

    }



    /**

     * 删除记录

     * @access public

     * @param array $options 表达式

     * @return false | integer

     */

    public function delete($options=array()) {

        $this->model  =   $options['model'];

        $sql   = 'DELETE FROM '

            .$this->parseTable($options['table'])

            .$this->parseWhere(!empty($options['where'])?$options['where']:'')

            .$this->parseOrder(!empty($options['order'])?$options['order']:'')

            .$this->parseLimit(!empty($options['limit'])?$options['limit']:'')

            .$this->parseLock(isset($options['lock'])?$options['lock']:false)

            .$this->parseComment(!empty($options['comment'])?$options['comment']:'');

        return $this->execute($sql,$this->parseBind(!empty($options['bind'])?$options['bind']:array()));

    }



    /**

     * 查找记录

     * @access public

     * @param array $options 表达式

     * @return mixed

     */

    public function select($options=array()) {

        $this->model  =   $options['model'];

        $sql        =   $this->buildSelectSql($options);

        $result     =   $this->query($sql,$this->parseBind(!empty($options['bind'])?$options['bind']:array()));

        return $result;

    }



    /**

     * 生成查询SQL

     * @access public

     * @param array $options 表达式

     * @return string

     */

    public function buildSelectSql($options=array()) {

        if(isset($options['page'])) {

            // 根据页数计算limit

            if(strpos($options['page'],',')) {

                list($page,$listRows) =  explode(',',$options['page']);

            }else{

                $page = $options['page'];

            }

            $page    =  $page?$page:1;

            $listRows=  isset($listRows)?$listRows:(is_numeric($options['limit'])?$options['limit']:20);

            $offset  =  $listRows*((int)$page-1);

            $options['limit'] =  $offset.','.$listRows;

        }

        if(C('DB_SQL_BUILD_CACHE')) { // SQL创建缓存

            $key    =  md5(serialize($options));

            $value  =  S($key);

            if(false !== $value) {

                return $value;

            }

        }

        $sql  =     $this->parseSql($this->selectSql,$options);

        $sql .=     $this->parseLock(isset($options['lock'])?$options['lock']:false);

        if(isset($key)) { // 写入SQL创建缓存

            S($key,$sql,array('expire'=>0,'length'=>C('DB_SQL_BUILD_LENGTH'),'queue'=>C('DB_SQL_BUILD_QUEUE')));

        }

        return $sql;

    }



    /**

     * 替换SQL语句中表达式

     * @access public

     * @param array $options 表达式

     * @return string

     */

    public function parseSql($sql,$options=array()){

        $sql   = str_replace(

            array('%TABLE%','%DISTINCT%','%FIELD%','%JOIN%','%WHERE%','%GROUP%','%HAVING%','%ORDER%','%LIMIT%','%UNION%','%COMMENT%'),

            array(

                $this->parseTable($options['table']),

                $this->parseDistinct(isset($options['distinct'])?$options['distinct']:false),

                $this->parseField(!empty($options['field'])?$options['field']:'*'),

                $this->parseJoin(!empty($options['join'])?$options['join']:''),

                $this->parseWhere(!empty($options['where'])?$options['where']:''),

                $this->parseGroup(!empty($options['group'])?$options['group']:''),

                $this->parseHaving(!empty($options['having'])?$options['having']:''),

                $this->parseOrder(!empty($options['order'])?$options['order']:''),

                $this->parseLimit(!empty($options['limit'])?$options['limit']:''),

                $this->parseUnion(!empty($options['union'])?$options['union']:''),

                $this->parseComment(!empty($options['comment'])?$options['comment']:'')

            ),$sql);

        return $sql;

    }



    /**

     * 获取最近一次查询的sql语句 

     * @param string $model  模型名

     * @access public

     * @return string

     */

    public function getLastSql($model='') {

        return $model?$this->modelSql[$model]:$this->queryStr;

    }



    /**

     * 获取最近插入的ID

     * @access public

     * @return string

     */

    public function getLastInsID() {

        return $this->lastInsID;

    }



    /**

     * 获取最近的错误信息

     * @access public

     * @return string

     */

    public function getError() {

        return $this->error;

    }



    /**

     * SQL指令安全过滤

     * @access public

     * @param string $str  SQL字符串

     * @return string

     */

    public function escapeString($str) {

        return addslashes($str);

    }



    /**

     * 设置当前操作模型

     * @access public

     * @param string $model  模型名

     * @return void

     */

    public function setModel($model){

        $this->model =  $model;

    }



   /**

     * 析构方法

     * @access public

     */

    public function __destruct() {

        // 释放查询

        if ($this->queryID){

            $this->free();

        }

        // 关闭连接

        $this->close();

    }



    // 关闭数据库 由驱动类定义

    public function close(){}

}